Chinese media reported the rumble was detected on the same site as previous tests, but a South Korean weather service was quick to say it could have been a “natural” quake.

An anonymous official from the South Korean agency said the analysis of seismic waves and the lack of sound waves suggested it wasn’t caused by an artificial explosion.

Nuclear watchdog CTBTO later said it had detected two seismic events but added that they were probably not deliberate explosions in the isolated country.

The site of the earthquake is where on September 3 North Korea conducted its sixth and most powerful nuclear test, which it claimed saw the detonation of a thermonuclear weapon.

Today’s quake was smaller than those recorded during previous tests, which have reached 6.3 magnitude.

Later reports emerged that the earthquake was likely an aftershock from the hermit state’s missile test on September 3, a nuclear test ban watchdog and other experts said.

Lassina Zerbo, executive secretary of the Comprehensive Nuclear Test Ban Treaty Organisation (CTBTO), tweeted the quake was “unlikely Man-made! Similar to ‘collapse’ event 8.5 mins after DPRK6”, a reference to the second tremor that followed the September 3 test.

“The most probable hypothesis at present is that this is a consequence of the previous event, which was of a significant magnitude and may still have repercussions in a fracture zone,” Zerbo told AFP.

The reports came after a raging Kim Jong-un lashed out at US rival Donald Trump labelling him “mentally deranged dotard” in a rare personal statement.

His comments were later clarified when North Korean foreign minister, Ri Yong Ho, said it could mean that the country would test a hydrogen bomb in the Pacific Ocean.

The North Korean leader said he will consider the “highest level of hard-line countermeasure in history” in response to Trump’s threat to “totally destroy” his rogue state which Kim sees as a “declaration of war.”

Addressing supporters at an Alabama rally today, Trump said Kim Jong-un “should have been handled a long time ago” branding him “little rocket man”.

But Russia appeared to call for calm as Moscow’s Minister of Foreign Affairs Sergei Lavrov said that action is needed “to calm down the hotheads”.

News of the quake came as Iran announced it had successfully tested a medium range missile after Trump fired criticism at its nuclear programme at the UN.

State TV showed the launch of a Khoramshahr missile, which has a range of 2,000km.

Iranian President Hassan Rouhani said he would increase the country’s military might as a “deterrent” on Friday, as Trump continued to take a hard line on the nation.